Well, red-black trees and merge sorts don't grow on trees (ahem), even in a real word :) But yeah, those are gonna be tough to just come up with on the spot wi

Well, red-black trees and merge sorts don't grow on trees (ahem), even in a real word :) But yeah, those are gonna be tough to just come up with on the spot without actually studying them. On the other hand, OP could be talking about stuff like tree traversal and similar simple stuff that is also included in introductory CS courses. Edit: OP chimed in elsewhere in the comments, it's not even about CS stuff.